Iran has vowed a harsh response after a US air strike in Baghdad on Friday killed the Qassem Soleimani, commander of the Iranian Quds Force and engineer to extend Tehran's military influence in the Middle East.

The United States said the raid was aimed at disrupting an "imminent attack" that would endanger the lives of its citizens in the Middle East.

Below we review the chronology of major events and turns in the course of relations between Iran and the United States:

1953
The US Central Intelligence Agency (CIA) arranged the overthrow of Iranian Prime Minister Muhammad Mossadegh, and restored power to Shah Mohammad Reza Pahlavi.

1957
The United States and Iran have signed an agreement for civilian nuclear energy cooperation.

1967
The United States provided Iran with a nuclear reactor, in addition to 93% enriched uranium fuel, a degree of purity that is used for making bombs.

1968
Iran has signed the Non-Proliferation Treaty, which allows it to have a civilian nuclear program in exchange for its commitment not to possess nuclear weapons.

1979

  • The revolution in Iran forced the American-backed Shah to flee, and Khomeini returns from exile and becomes the Supreme Leader of the Revolution.
  • Students took control of the US embassy in Tehran, and held its staff hostage.

1980

  • The United States cut diplomatic ties with Iran, withheld its assets and banned most trade with it.
  • The hostage-rescue mission ordered by President Jimmy Carter failed.

1981
Iran released 52 American hostages minutes after the end of Carter's term and the inauguration of Ronald Reagan as President of the United States.

1984
The United States included Iran in the list of state sponsors of terrorism.

1986
Reagan unveiled a secret arms deal with Tehran in violation of the US arms embargo.

1988
An American warship accidentally drops an Iranian passenger plane over the Gulf, killing all 290 passengers and crew.

2002

  • President George W. Bush declared the "axis of evil" and included Iran, Iraq, and North Korea.
  • US officials have accused Tehran of working on a secret nuclear weapons program.

2006
Washington has declared its willingness to join multilateral nuclear talks with Iran if the latter halts verifiable nuclear enrichment activities.

2008
Bush sent for the first time an official to participate directly in nuclear negotiations with Iran in Geneva.

2009

  • US President Barack Obama has told Iran's leaders that he will reach out if they "loosen their grip".
  • Britain, France and the United States have announced that Iran is building a secret uranium enrichment site in Fordow.

2012

  • A US law was passed granting Obama the authority to impose sanctions on foreign banks if they did not clearly limit Iran's oil imports.
  • Iranian oil sales decreased, resulting in an economic slowdown.
  • US and Iranian officials begin secret talks.

2013

  • Hassan Rouhani was elected president of Iran on the basis of a program to improve relations with the world and boost its economy.
  • Obama and Rouhani made the phone, the highest level of contact between the two countries in three decades.
  • Iran and six major powers reach a nuclear agreement known as the Joint Work Plan Agreement.
  • Iran has agreed to limit its nuclear activities in exchange for limited sanctions relief.

2016

  • Iran has released ten American sailors who entered Iranian territorial waters.
  • The United States and Iran conducted a prisoner exchange.

2018
US President Donald Trump withdrew from the nuclear deal in May and reimposed economic sanctions on Iran.

2019

  • The United States designated the Iranian Revolutionary Guard "terrorist organization" in April.
  • Iran says it will increase the production of enriched uranium, in easing its obligations under the nuclear agreement.
  • Oil tankers are under attack in the Gulf in May and June.
  • The United States held Iran responsible and Tehran denies.
  • Tehran shot down a US airliner in June, saying it had violated Iranian airspace, and it seized a British oil tanker in July.
  • Saudi state oil company has been attacked by drones and missiles believed to have been launched from Iran, and Tehran denies involvement.
  • Attacks on American military bases in Iraq result in the death of an American, and the United States holds responsibility for armed groups backed by Tehran inside Iraq, and attacking their bases.
  • Protesters demonstrated outside the US embassy in Baghdad and stormed it.